By "dropping through the rope," do you mean you can't grab the rope? You just jump and hit "up" to grab the rope as you normally would. You can grab it from the beginning and test it without jumping toward the spikes. The hard part is avoiding the spiky ball. If the ball hits you, you fall off the rope. You have to just time it since you don't seem to be able to destroy it. Also make sure to kill the wasps and destroy the hive before starting. Then as you slide down the rope and let go at the right time to land on the platform.